In the concrete pouring business, it is typical to utilize concrete boom pump trucks for large-scale jobs. A typical concrete boom pump truck contains a series of booms that allow the concrete to be delivered great distances away from the pump truck. A universal problem in the use of boom pump trucks is the absence of any method or device to adequately control the flow of concrete from the boom to the intended destination
A typical boom pump truck is depicted in FIG. 1, and includes a concrete pump and a series of booms. In use, a typical arrangement includes three boom segments that extend upwardly from the pump truck to an apex, followed by one boom segment that extends downwardly from the apex. At the end of the last boom segment there is often a discharge delivery hose, often referred to as a “tip hose,” from which the concrete exits to its destination.
A common concrete pumping scenario requires that a large number of discrete holes be filled with concrete, as may be needed during the pouring of pilings in a foundation. For such a situation, it is typical to have one operator whose job it is to control both the operation of the concrete pump and the location of the boom, and a second operator whose job is to handle the tip hose and hold it in position above the destination intended for the concrete. Specifically, the pump operator will position the boom such that the tip hose is directly above the hole to be filled. The pump operator will turn the pump on, causing concrete to flow up the first two sections of the boom system, past the apex, down the next two sections of the boom, and out the tip hose into the hole. All the while, the tip hose operator will handle the tip hose. Once the hole is close to being filled, the tip hose operator signals the pump operator to turn the pump off. At this point, all of the concrete that is below the apex in the boom system will fall, by force of gravity, down the third and forth sections of the boom, out the tip hose, and into the hole. The pump operator will then move the boom, while the tip hose operator accompanies it to the next destination, and the process will start over.
As can be appreciated by the foregoing, it is important that the operation of the pump be synchronized with the placement of the tip hose. Presently, this translates into the pump operator and the tip hose operator having to work in unison. Specifically, the pump operator must be careful to not start the pump, and thus begin pumping concrete, until the tip hose operator is ready with the tip hose in position. Likewise, after a hole is filled, the tip hose operator must be careful not to move the tip hose away from the hole or other destination until all of the concrete below the apex has fallen, and the tip hose is empty.
In addition to the need for working close together with the tip hose operator, the pump operator must also be adept at judging exactly when to turn the pump off. Specifically, it is often difficult for the pump operator to accurately estimate the specific time to turn the pump off, such that the amount of concrete in the system below the apex will be sufficient to fill the hole. Rather, it is common for the pump operator to turn the pump off too soon, resulting in the hole not being completely filled, or alternatively, to turn the pump off too late, resulting in concrete overflowing the hole. These challenges are made even more difficult by the fact that the boom system contains a large amount of heavy concrete. Once the pump is turned off, the draining of the boom system from the apex downward causes the entire boom system to lift vertically as the concrete empties, thus making it even more difficult to judge exactly when to turn the pump off to result in the precise amount of concrete being pumped. This movement also increases the challenge that the tip hose operator faces in controlling the tip hose.
An obvious shortcoming that has not been solved by the prior art, is the pump operator's need to estimate the specific amount of concrete that is beyond the apex, and thus available to flow out of the tip hose, at the time he turns the pump off. A device is needed which will allow the pump operator more accurate control of the amount of concrete delivered during a given cycle.
It is known in the prior art to reduce the variability in the amount of concrete delivered by having the tip hose operator put a “kink” in the tip hose when the operator desires to stop the flow of concrete. Of course, such an action must be taken only in conjunction with the pump operator turning the pump off, as to fail to do so could result in the tip hose operator having to overcome the force of the concrete being pumped when attempting to place a kink in the tip hose. Placing a kink in the tip hose when the concrete pump is still running is a very dangerous situation, and can result in a catastrophic failure of the tip hose under pressure. A device is needed which will provide increased control of the amount of concrete delivered which does not incur the additional risks of a ruptured tip hose.
Other devices are known to control the flow of concrete in a flexible hose. For instance, in U.S. Pat. No. 5,105,981, issued to Gehman, is disclosed a particulate matter dispenser. Included in the dispenser is a flexible discharge tube at the base, which permits particulate matter to flow out of the dispenser. The flexible tube extends through an aperture in a base plate. One face of the aperture has a projecting portion, which constitutes a fixed clamp. This fixed clamp cooperates with a moveable clamp connected to a linkage, and this allows the user to open and close the flexible tube. In order to permit the flow of material at certain designated times, the linkage is actuated, causing the flexible clamp to be moved away from the fixed clamp and thus decompress the hose, thereby allowing flow through the hose until the flexible clamp is returned.
Similarly, U.S. Pat. No. 4,893,966, issued to Roehl, discloses a component which serves to squeeze a hose containing a granular dry material, thus preventing the flow of the material through the hose. The hose squeezing means consists of rounded elongated squeezing elements which are arranged parallel to each other on either side of the hose. One of the two squeezing elements is connected via a fork shaped linkage to a piston rod which drives the element into the path of the hose, while the other element is connected to the housing of the working cylinder.
Although the discharge tube control devices may be appropriate for large pieces of heavy equipment, they are too heavy and difficult to move to be of any use in conjunction with a boom pump truck.
One device known in the prior art is disclosed German Patent No. DE 33 10 176 C2, issued to Bylund, discloses a mouth piece for the delivery of concrete, and other semi fluid materials of particular use, in pumping concrete under water. Specifically, there is disclosed a system consisting of two rigid pipes in axial succession, connected by a flexible tube. This combination is surrounded by an outer pipe, with space between the inner pipes and tube on the one hand, and the outer pipe on the other hand, is pneumatically sealed and connected to a pressure medium. By pumping air into the cavity, the flexible tube is compressed, thus preventing the flow of concrete through it.
There is also disclosed in the Bylund patent, support strips arranged on the inside of the outer pipe, and leading to the outer periphery of the flexible tube, which serves a purpose of insuring that the flexible tube remains in exactly its cylindrical, relaxed position when the valve is opened. An alternative embodiment is disclosed, wherein the support strips are replaced with a continuous pipe located about the periphery of the flexible tube. This peripheral pipe includes large openings which allow air to pass, and therefore act open, the flexible tube when it is desired to prevent the flow of material.
One drawback of the device disclosed in the Bylund patent, is that it is very heavy. As a result, it adds increased strain on the boom system. Another drawback is that the flexible mechanism is exposed to the concrete or other slurry material. This drawback, in combination with the fact that the pressure medium acts directly upon it, is likely to result in the flexible hose wearing out quickly. Replacement of the flexible hose would require disassembly of the device. There is a need for a system wherein the hose for conveying the concrete is not acted upon directly by the pressure medium.